Prime-mover-generator plant



Sept. 23, 1930. A BEEKMAN 1,776,716

PRIME MOVER GENERATOR PLANT Filed Feb. 25, 1928 luv/cantor:

Royc 7\. Beekman, yM ZZQRJ Patented Sept. 23, 1930 UNITED STATES PATENTOFFICE ROYCE A. BEEKMAN, OF SCHENECTADY, NEW YORK, ASSIGNOR TOGENERAL,ELECTRIC COMPANY, A CORPORATION OF NEW YORKIRIME-MOVER-GENERATOR PLANT Applicationfiled February 25, 1928. serialNo. 257,055.

My invention relates to prime-mover-generator plants wherein a primemover constructed and arranged for a given direction of rotation andsubject to damagewhcn rotated in the reverseddirection is used to drivea generator which, due to its connection in a power system, is subjectto a motoring action with reversed rotation upon failure of its primemover to supply the necessary torque to drive it as a generator.

An object of my invention is to provide means for preventing suchreversal and the consequent damage attending it.

In ship propulsion systems, especially where it has been found desirableto use Diesel engines, it is common practice to provide a plurality ofgenerating units because the smaller engines may be more easilyconstructed, installed and repaired. Furthermore, such arrangementsprovide more ecopairing them without incapacitating the ship or undulyslowing up its schedule.-

In the case of direct current systems it has been found desirable toconnect several generators in series with one another in order toeliminate or compensate for speed variations of the several primemovers. \Vhen, however, the generators are thus connectedtherc is thepossibility that any one of the generators may motor with reversedrotation whenever its prime mover for any reason fails to supply thenecessary torque to drive it as a generator. Certain types of primemovers may be constructed for rotation in either d1- rection but aremore cheaply constructed for rotation in a given direction. Such is thecase of the Diesel engine. In I either case, however,'the prime mover issubject to damage When rotated in a direction .opposlte to the directionin which it is normally arranged to function. i

mover or to permit it to recover and continueto run driving itsgenerator as a generator and supplying power to the system. In thismanner I am able to prevent a reversal of the prime mover.

My invention will be better understood from reference to the followingdescription when considered in connection with the accompanying drawingand its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 shows a simplified diagram ofconnections diagrammatically illustrating a system in which my inventionhas been applied, and Figs. 2 and 3 show details of a switch mechanismwhich may be used in said system.

Fig. 1 shows a propeller motor 1 provided with a separately excitedfield 2 and arranged to be supplied with current from generators 3driven by suitable prime movers 4, such as Diesel. engines; Thegenerators 3 are connected in series with one another and with thepropeller motor 1 by conductors 5, 6, 7 and 8. Switching means may beprovided in this circuit for shorting out any generator or fordisconnecting the motor from the generator, but since such arrangementsare already well known and form no part of the present invention thediagram has not been complicated by illustrating them. The se eralgenerators 3 are provided, with separately excited fields 9 which areconnected through conductors 10 and 11 tobuses 12 and 13 which, in turnare connected to a potentiometer 14. This potentiometer 14 is connectedacross a suitable source of supply 15 by conductors 16 and 17 and isadapted to regulate simultaneously the amount and direction of theexciting current supplied to the several fields of the severalgenerators. In the circuit of each generator field is an adjustingrheostat 18 and a cutout shown as a relay 19. The operating coil of therelay 19 is connected across the source of supply 15 through conductor20, contacts 21 and contact member 22 of a switch mechanism 23, andconductors 2 1 and Contact member 22 is normally biased against anabutment 26 by a weight or a spring 27 but upon the correct rotation ofthe prime mover dis moved against the contacts '21 to complete thecircuit of the relay l9which then closes and completes the field circuitof the generator 3 driven by the prime mover 1. Motor field 2 isconnected acrossthe source of supply 15 by conductors 28 and 29 and itsdegree of excitation is controlled by'means of a rheostat '30 insertedin series with it.

The switch mechanism .43 may be of any suit-able construction so long asit will maintain its contacts close lwl1en the prime mover with whichitis connected rotates in one direction and breaks this connection whenthe prime mover'slows down. abnormally or its direction of rotation isrev rsed a few de-. grees'. agrammatically illustrated in Figs. 2 and 3.

The construction may be such'as di- Referring to these figures, it willbe noted that as there illustrated the switch mechanism comprises twodisks 31 and 32 placed in close proximity to one another with theirlower portions immersed in a heavy oil 33.

' One of the disks 31 is free to rotate about its centerwhile the otherdisk 32 is free to rotate between contacts 21 and abutment 26 againstwhich it is normally biased by the spring 27, previously referred to.The disk 31 which is free to rotate is mechanically connected directlyor through the agency of gears to the shaft of the prime movers 4.Usually it will be found desirable to have the disk 31 rotate at agreater speed than the prime mover. When the prime mover is rotated inthe correct direction at a proper speed this disk will also be rotatingin a corresponding direction and will exert a dragging effect ontheother disk 32, due to the viscosity of the oil 33, with the resultthat the contact member 22 mounted on disk 32 will be moved against theforce of the spring 27 into engage ment with contacts 21 whichareshorted thereby. As previously noted above, this completes the circuitof relay 19 which closes and completes the circuit of the field 9 of thegenerator 3 driven by the prime mover 4. The switch mechanism abovebriefly described is in accordance with the invention or" George R.Townsendwhose application Serial No. 75,147, tiled Dec. 12, 1925, forrotary switch mechanism, now Patent 1,677,-

008, granted July'lO, 1928, is assigned to the assignee of the presentapplication.

The operation of the system described is as follows: The prlme moversare started and aslong as they rotate in the correct" dlrectlons theswitch mechanisms 23 directly completing the circuits of the field coils9 'otthegenerators 3. Thereafter the degree of excitation of thegenerators is simul taneously controlled through the potentiometer 14;.Individual adjustments may be made in each tieid circuit-by means of therheostats 18. The direction of rotation 01 the propeller motor 1 maythus be controlled according to the well known ard Leonard system bymeans of the potentiometer 1i. Provlslon is also made for controllingthe field of the motor 1 by means'of the rheostat 30 so that undervarious conditions the motor 1 may be properly adjusted forobtaining thebest'results. r

If for any reason one of the prime movers i-should slow down abnormallyor stall due to the failure of fuel supply or for some "other reason orotherwise lose its propelling torque, its corresponding generator 3 willtend to motor and rotate theprime mover 1 in a direction opposite tothat in which it has beenrotating. Howev'en-as soon as this reversal 1sinitiated, and by thls D mean that the prime mover has slowed downabnormally or actually reversed a tew-degrees, the switch mechanism23operates to open the circuit of the relay 19 which upon openingdeenergizes the held 9 of the generator 3 which is motoring. Thisdeenergizes the generator 'andprevents it from-motoring further, thuspermitting the prime mover either to come to-rest or under certainconditions even to recover and "again supply power tothe system.

It is a-pparent to those skilled in-the art that the proposedarrangement may be modified to meet varyingv requirements withoutdeparting from my invention which has been shownand described inconnection with a simplified arrangement for thepurpose of clearlyillustrating the invention and I, therefore, aim in the appended claimsto cover all such changesand modifications as fall within the truespirit and scope of my invention.

What I claim asnew and desire to secure by Letters Patent of the United.States, is: 1. A prime-mover-generaton plant includingagenerator subjectto reverse rotation due to motoring action, a primemover for saidgenerator adapted for rotation in a given' direction only, and meansmechanically connected to saidprime mover, responsive when the primemover slows down abnormally and before 1ts speed approacheszero, fordeenergizlng said generator :when it :tends -to reverse the direction ofrotationof-said prime mover.

2. In a ship propulsion sy-stem, a propeller motor, aplurality of seriesconnected generators for suplying power to said propeller motor, aplurality of prime movers adapted for rotation in a given direction onlyfor independently driving said generators, and means mechanicallyconnected to each of said prime movers for deenergizing itscorresponding generator just before its speed approaches zero due to themotoring action of its generator upon a failure of its prime mover.

3. In a ship propulsion system, a propeller motor, a plurality of seriesconnected generators for supplying power to said propeller motor, meansfor exciting each of said generators, a plurality of prime moversadapted for rotation in a given direction only for independently drivingsaid generators, switching means associated with each of said primemovers for controlling the can citation of the generator driven thereby,means for biasing each of said switching means to the position in whichit deenergizes the generator with which it is associ ated, and meansconnecting each of said switching means to its associated prime moverfor overcoming said biasing means during rotation of said prime moveruntil just before its speed approaches zero due to the motoring actionof its connected generator.

In Witness whereof, I have hereunto set my hand this 2%Lth day ofFebruary, 1928.

ROYCE A. BEEKMAN.

